iZettle, the “Square of Europe” that has been rolling out its dongle-based mobile payments service in Scandinavia and is currently trialling in the UK, is now extending its service once again: it’s launching an API so that third-party iOS app makers can integrate its payment service directly into their apps. An Android solution is due later this year, the company tells me.

Although Square does not directly compete with iZettle at the moment — Square has yet to extend outside the U.S., and iZettle’s still only in Europe — it looks like iZettle has stolen a march on Square in terms of functionality, letting merchants offer the iZettle payment platform wherever their apps are used, and not just at the point of sale, where iZettle’s own app would get used.

iZettle’s spokesperson notes to me that Square did appear to try something out like this a while back…